The present invention relates to a fifth wheel hitch for receiving a kingpin of a trailer and one which has the ability to sense forces between the trailer bolster plate, kingpin and the fifth wheel and a circuit to process such sensed information.
The identification of forces between a truck trailer and a truck hitch is useful for a variety of reasons. Such information can be employed, for example, in an automatic braking system whereby signals from a sensing system can be employed to prevent excessive braking on one or more wheels or otherwise control braking for safe acceleration. In addition, such systems are helpful in alerting the vehicle operator to excessive trailer movement, such as pitching, yaw and/or potentially dangerous roll conditions.
As can be appreciated, the interconnection between a trailer kingpin and a fifth wheel assembly provides a relatively harsh environment for detection of the large forces involved and efforts to provide accurate sensing information with signals from a sensor which are linearly related to the detected forces has been difficult. U.S. Pat. Nos. 5,286,094 and 5,289,435 represent one sensor construction and a mounting employed for measuring push and pull forces on a hitch connection. It would be desirable, however, to provide additional information such as pitch, yaw and roll information for use by the driver in safely operating the vehicle.
The sensing of multiple axis force information between the coupling of a trailer to a tractor is difficult not only due to the harsh environment to which the equipment is exposed but also the relatively large and rapidly varying forces encountered and finally the difficulty in providing a linear output signal from sensors which may be employed.